We propose Spectrum Aware Virtual Coordinate (SAViC) for multi hop cognitive radio network (CRN) to facilitate geographic routing. The proposed virtual coordinates (VC) of any two secondary users reflect both geographic distance and opportunistic spectrum availability between them. As a result, geographic routing is able to detour the area affected by licensed users or cut through the area with more available spectrum. According to different spectrum occupation patterns of primary user, two versions of SAViC are designed based on the channel utility and primary user's sojourning time respectively. Simulation shows the proposed virtual coordinate facilitates geographic routing to achieve high success rate of path construction. When duty cycle on the licensed channel is heterogeneous in the network, channel utility based virtual coordinate supports geographic routing to outperform a state-of-the-art geographic routing protocol by 40% on packet delivery ratio. When the channel utility is identical on each secondary node, and the sojourning time of primary users for secondary users are different from each other, SAViC based on primary user's sojourning time achieves significantly shorter delay than other virtual coordinates.
Contemporary level of scientific and technical development is due to sharing relevant information and in this case, it is very important to organize access to various informational systems with protected informational resources. Implementation of right instruments for interaction with informational systems for research and educational communities is a real necessity and will have essential contribution to increase capacity for access to knowledge. In parallel, increasing amounts of data that was previously paper based is being digitised, while automated instruments are providing 24-hour streams of data on every imaginable subject. This ‘data deluge’ combines with changing practices to give the phenomenal growth and success of digital science, and must be faced to let us capitalise on these new sources of information. Current e-Infrastructures and their precursors have made use of many different technologies, and gone through several evolutions to reach a relatively stable state. This development has started from both specialized, subject-specific systems and very broad generic ones that are now meeting in a middle group, where there is a vision of interoperable services from many sources that can be integrated or blended to serve new purposes.
ATCA (Advanced Telecom and Computing Architecture) is an important progress in the field of high computational-power architectures. This platform has a high data transfer performance based on a hardware (HW) standard frame: backplane compliant with the regulations of PIGMG (PCI Industrial Computers Manufactures Group) with a common 40 Gbps “InfiniBand” Switching Fabric behind, to be used by computing, telecom or instrumentation front boards taking benefit of very large bandwidth for local transfers. These assets ensure a great scalability and versatility for the telecommunications industry and are making ATCA ideal for large implementations and load & stress enduring applications. For these reasons, the necessity of a test-bed environment based on an ATCA rack is proven, also as a “sand-box” for innovation and validation of new services. Student education and integration to the job market can benefit a lot from these high-tech platforms. There are three key-parts of modern education in technology – emulation, simulation, and remote access. Software emulation of telecom subsystems is something that ATCA is very suitable for, due to its high performance and modularity. The remote access to real high-tech platforms is the topic of this paper ; given the capability of these platforms for multiplexed access, they are ideal for both concurrent access for service integration and hands-on learning and “training-on-the-job”, despite being too expensive to be limited to didactical use. After our initial observations and analysis, that proved ATCA to be an important building-block for a future endeavor in the field of telecommunication, we have designed a work-bench using our dedicated ATCA platform for educational purpose, and transforming it in a IaaS - Infrastructure as a Service. The challenge proved to be the conversion of the industry-designed equipment (no down time), into a DUT (device under test) with systolic software sessions. This also meant that high project turnover had to be made possible, so an automatic cloning mechanism was implemented. The key features of our development environment are: Flexible access and research on the system – the ATCA platform is well-suited for IaaS cloud (Infrastructure-as-a-Service): it can be configured, operated and exploited locally and also remotely, due to our implementation. The Network Back-up & Restore capability - the concept of “ services factory” : user work can be saved after each work session. These projects can afterwards be reloaded, executed and viewed remotely allowing an international audience and development. HW Scalability and Remote Control - the different blades can be inserted for various functions while a unique shelf manager board maintains a central control of the platform. This leads to an secure outside access, enabling the coexistence of research and educational sessions Infrastructure Network Integration - the platform access was divided in two categories: via local serial interfaces, in the administration network and the Ethernet interfacing via a router that represents the production network. Relayed power switch - a robust switch on/off of the power sources based on strong relays Remote access to the Service Factory Mobile access - a smartphone mobile access mechanism was implemented Systolic-Enabled Functioning - in order to ensure reliable working sessions and safeguarding of the applications backup and restore procedures were devised Research Capabilities DPI (Deep Packet Inspection) - with the PP50 dedicated board - real time scanning of the traffic payload DSP (Digital Signal Processing) - ATCA-9100-TI blade - a powerful architecture to enable media processing for thousands of channels Core and Radio capabilities Cloning mechanism - that extendable system was implemented in order to allow multi-user capabilities, transforming the platform into a scientific web-based laboratory, a service factory where several types of projects can be developed in parallel. In our efforts to ensure a reliable, secure remote-access, we chose the NX technology that provides remote X Window System connections at improved performance even for slower links. This modern SSH-based technology makes sessions as responsive as possible, at a high level of security. Our remotely-accessible advanced computing and telecom platform is aimed as a testing “Sand-Box”, useful for post-graduate education and research projects. The IaaS (Infrastructure-as-a-Service) capabilities are published according to the principles of “PnP” (Plug-and-Play) in the Cloud based on XMPP – “Extensible Messaging and Presence Protocol” (RFC 6120) for “Social Networking” in IoT (the “Internet of Things”). As for the PaaS („Platform as a Service”) capabilities, there were integrated the SW solutions „open BSC (Base Station Controler) ”, „open GGSN (Gateway GPRS Support Node)” and „open IMS (IP Multimedia Server)” in a Telecom „APS – Application Programs System” that is more than an open OS (Operating System); it implements the basic Call-Control functionality of a fixed-mobile convergent Core Network combined with the Service Control Point functionality of an Intelligent Network. Further development is oriented towards „Software Radio Functionality” by a powerful combination with a professional IQ-producer for digital modulation integrating an Anritsu MG3700A multi-standard generator (up to 6GHz) (see figure 1), taking also into-consideration „load & stress” capabilities for traffic generation.
